Question

45 is what percent of 90?

Answer 1

`45` is `50%` of `90`.

Explanation:

`45/90 = x/100`, where `x` is the percentage.

`90x = 4500 => x = 50`.

Equations of the form `a/b = c/d` can be transformed to `ad = bc`.

In general, for any `a, b` with `b!=0`, from the equation `a/b = x/100`,

`x` shows you what percentage `a` is, of `b`.